Global concern over widely documented declines in pollinators^1,2,3 has led to the identification of anthropogenic stressors that, individually, are detrimental to bee populations^4,5,6,7. Synergistic interactions between these stressors could substantially amplify the environmental effect of these stressors and could therefore have important implications for policy decisions that aim to improve the health of pollinators^3,8,9. Here, to quantitatively assess the scale of this threat, we conducted a meta-analysis of 356 interaction effect sizes from 90 studies in which bees were exposed to combinations of agrochemicals, nutritional stressors and/or parasites. We found an overall synergistic effect between multiple stressors on bee mortality. Subgroup analysis of bee mortality revealed strong evidence for synergy when bees were exposed to multiple agrochemicals at field-realistic levels, but interactions were not greater than additive expectations when bees were exposed to parasites and/or nutritional stressors. All interactive effects on proxies of fitness, behaviour, parasite load and immune responses were either additive or antagonistic; therefore, the potential mechanisms that drive the observed synergistic interactions for bee mortality remain unclear. Environmental risk assessment schemes that assume additive effects of the risk of agrochemical exposure may underestimate the interactive effect of anthropogenic stressors on bee mortality and will fail to protect the pollinators that provide a key ecosystem service that underpins sustainable agriculture.

全球对广泛记录的传粉媒介减少^{1,2,3 的}关注导致了对人为压力源的识别，这些压力源单独对蜜蜂种群有害^4,5,6,7。这些压力源之间的协同相互作用可以大大放大这些压力源的环境影响，因此可能对旨在改善传粉者健康的政策决策产生重要影响^3,8,9. 在这里，为了定量评估这种威胁的规模，我们对来自 90 项研究的 356 种相互作用效应大小进行了荟萃分析，在这些研究中，蜜蜂暴露于农用化学品、营养应激源和/或寄生虫的组合。我们发现了多种压力源对蜜蜂死亡率的整体协同效应。蜜蜂死亡率的亚组分析揭示了当蜜蜂在实地现实水平下接触多种农用化学品时协同作用的有力证据，但当蜜蜂接触寄生虫和/或营养应激源时，相互作用并不大于累加预期。所有对适应性、行为、寄生虫负荷和免疫反应的代理的交互作用都是相加的或拮抗的；因此，驱动所观察到的蜜蜂死亡率协同相互作用的潜在机制仍不清楚。